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Topic: Determine the equilibrium constant Kp???  (Read 4181 times)

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Offline webassignbuddy

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Determine the equilibrium constant Kp???
« on: October 23, 2013, 06:25:09 AM »


I did: Kp = Kc x (RT)^(n_g)

KP = (0.25/3^4)(0.08206 x 1325)^-3
Kp = (0.00308642)(108.7295)^-3
Kp = 2.0 x 10^-19 (INCORRECT)

:(:(:(:( this is frustrating bc the answer is supposed to be 324....

Offline sjb

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Re: Determine the equilibrium constant Kp???
« Reply #1 on: October 23, 2013, 07:04:48 AM »
Have you used the right R?

Offline Borek

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Re: Determine the equilibrium constant Kp???
« Reply #2 on: October 23, 2013, 07:19:38 AM »
I did: Kp = Kc x (RT)^(n_g)

And where did you got Kc from?

Quote
KP = (0.25/3^4)(0.08206 x 1325)^-3

0.25 and 3.0 are pressures, not concentrations.
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Offline webassignbuddy

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Re: Determine the equilibrium constant Kp???
« Reply #3 on: October 23, 2013, 08:19:14 AM »
Have you used the right R?

Yes that's what my textbook used in a similar example! :(

Offline webassignbuddy

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Re: Determine the equilibrium constant Kp???
« Reply #4 on: October 23, 2013, 08:23:37 AM »
I did: Kp = Kc x (RT)^(n_g)

And where did you got Kc from?

Quote
KP = (0.25/3^4)(0.08206 x 1325)^-3

0.25 and 3.0 are pressures, not concentrations.

I know but you do

Kp = [PS8]/[PS2]4
Kp = [S8](RT)/[S2]4(RT)4
Kp = ([S8]/[S24])(RT)3-

Edit:

Oh wait!!! I was looking at the wrong answer key...
the answer is 3.08 x 103-

So all I do is

Kp = [PS8]/[PS2]4
Kp = 0.25/34
Kp = 0.003086
Kp = 3.08 x 103-

:D!!!

Offline webassignbuddy

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Re: Determine the equilibrium constant Kp???
« Reply #5 on: October 23, 2013, 08:42:29 AM »
I did: Kp = Kc x (RT)^(n_g)

And where did you got Kc from?

Quote
KP = (0.25/3^4)(0.08206 x 1325)^-3

0.25 and 3.0 are pressures, not concentrations.

For part B, I found:
Q = [S2]/[S8]4
Q = (1.8 x 10-3)/(9.76 x 10-1)4
Q = 1.98 x 10-3 (CORRECT)

Since Q < K, ΔG is negative and the reaction is SPONTANEOUS (to the right) (CORRECT)

How do I calculate Kc though? :( Because it's not Kc = [S2]/[S8]4

Offline Borek

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Re: Determine the equilibrium constant Kp???
« Reply #6 on: October 23, 2013, 09:01:59 AM »
You know how to find Kp when Kc is given, but you don't know how to find Kc when Kp is given?
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Offline webassignbuddy

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Re: Determine the equilibrium constant Kp???
« Reply #7 on: October 23, 2013, 09:17:22 AM »
You know how to find Kp when Kc is given, but you don't know how to find Kc when Kp is given?

Ohh!!

Kc = Kp x (RT)-Δng
Kc = 3.96 x 103

Thanks!

I may have one more question! :o

Offline webassignbuddy

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Re: Determine the equilibrium constant Kp???
« Reply #8 on: October 23, 2013, 09:24:25 AM »
You know how to find Kp when Kc is given, but you don't know how to find Kc when Kp is given?

How would I go about finding ΔG°?

Offline webassignbuddy

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Re: Determine the equilibrium constant Kp???
« Reply #9 on: October 24, 2013, 08:10:55 AM »
You know how to find Kp when Kc is given, but you don't know how to find Kc when Kp is given?

do you know how I can find ΔG?

Offline webassignbuddy

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Re: Determine the equilibrium constant Kp???
« Reply #10 on: October 24, 2013, 08:58:17 AM »
Anyone?

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